Mouse models have become increasingly valuable for biomedical research, and their importance is particularly relevant to cystic fibrosis science as attested to by scores of publications describing studies performed on these models as a means to understand and treat the human disease. The Animal Models Core Facility provides a variety of mouse lines to CF P30 investigators, including previously generated and characterized strains that include the UNC (Cftr[tm1Unc]) and Cambridge (Cftr[tm1Cam]) Cftr knockout; Cftr-G551D (Cftr[Tm1G551D]); Cftr-F508del line (Cftr[Tm1Kth]); a transgenic (Tg) line expressing wild type human CFTR on a Cftr[-/-] background (hCFTR Cftr[-/-]), and a similar Tg mouse line expressing a human CFTR-G542X on a Cftr[-/-] background (hCFTR-G542X Cftr[-/-]). In addition to these established mouse lines available at our Center, we have assisted P30 investigators with the generation and/or breeding of several novel CF mouse models, including a Cftr-G542X knock-in line (Cftr[Tm1G542X]) and a Tg line expressing human CFTR-W1282X in a Cftr[-/-] background (hCFTR-W1282X Cftr[-/-]). A number of other murine lines are presently under construction in Core B. The Animal Models Core also assists CF investigators by providing functional CFTR assays, including nasal Potential Difference (PD) measurements assays in live animals as well as intestinal short circuit current assays of freshly excised tissues. The overall purpose of the Animal Models Core is to provide all necessary murine resources for the successful completion of individual P30 projects, and to perform advanced physiologic and other testing of CF animal models. These resources allow investigators to examine CF disease mechanism in vivo, and facilitate preclinical evaluation of experimental therapeutics for the disease. Thus, the Animal Models Core is an indispensable component of the overall P30.